U.S. Pat. No. 4,754,247 entitled "Molded Case Circuit Breaker Accessory Enclosure" describes a so-called "integrated" circuit breaker that provides both circuit interruption as well as accessory function. This patent should be reviewed for its disclosure of an accessory cover mounted on the circuit breaker cover for providing access to field-installable accessory devices. The integrated circuit breaker includes an integrated circuit electronic trip unit which allows one circuit breaker design to be used over a wide range of ampere ratings in combination with a rating plug, also mounted in the circuit breaker cover. The electronic trip unit is described within U.S. Pat. No. 4,589,052 and the rating plug is described within U.S. Pat. No. 4,649,455.
Introduction of such integrated circuit breakers within the world market has raised some interesting considerations with regard to the various and sundry International Electrical standards which cover most of the European and Asian countries.
The use of common circuit breaker components over a wide variety of International-listed ampere ratings could produce a strain on the circuit breaker cover in the vicinity of the arc chute when a lower rated circuit breaker cover is used with a higher rated circuit breaker operating mechanism.
International electric standards require that the circuit breaker handle remain in the ON position when the circuit breaker contacts are welded together and an attempt is made to reset the circuit breaker operating mechanism.
The addition of the fourth circuit breaker pole to commonly employed U.S. manufactured three pole industrial-rated circuit breakers further increases the amount of gaseous products produced during circuit interruption under severe overcurrent test conditions.
The purpose of the invention is to provide several adaptations to the integrated circuit breaker described earlier that would render the circuit breaker useful in any of the countries subscribing to the International Electric Code without requiring a complete and separate circuit breaker design for both the U.S. and foreign markets.